Conducting high transparency thin films based on single-walled carbon nanotubes

Abstract

Methods of making a single-walled carbon nanotube thin film, and the thin film which can be located on a substrate, and can have a resistance of less than 7500 ohm/square, and a transparency to 550 nm light of greater than 85%.

What we claim is: 
     
       1. A method of directly preparing thin films of carbon nanotubes comprising:
 providing a substrate having a top surface and a vertical axis therethrough; 
 contacting the substrate with an acetone solution and applying ultrasonic energy; 
 contacting the substrate with an isopropanol solution and applying ultrasonic energy; 
 flowing an inert gas over the substrate; 
 applying a carbon nanotube producing catalyst-containing solution to the top surface of the substrate; 
 spinning the substrate about its vertical axis, and reapplying catalyst-containing solution until a sufficient amount of carbon nanotube producing catalyst-containing solution is deposited on the top surface; 
 washing the substrate in a non-polar solvent; 
 positioning the substrate in a chemical vapor deposition apparatus; 
 heating the substrate to a temperature of from 800° C. to 900° C. sufficient to produce carbon nanotubes, and 
 contacting a carbon-containing gas with the heated substrate to produce a thin film of carbon nanotubes on the top surface. 
 
     
     
       2. The method according to  claim 1 , wherein the substrate comprises quartz. 
     
     
       3. The method according to  claim 1 , wherein the carbon nanotube producing catalyst comprises at least one metal selected from the group consisting of iron, cobalt, nickel, molybdenum, ruthenium, rhodium, palladium, silver and platinum. 
     
     
       4. The method according to  claim 1 , wherein the carbon nanotubes are comprised of a majority of metallic carbon nanotubes. 
     
     
       5. The method according to  claim 1 , wherein the carbon-containing gas contains at least one member selected from the group consisting of methane, ethane and propane. 
     
     
       6. The method according to  claim 1 , wherein the thin film of carbon nanotubes has a resistance of less than 7500 ohm/square. 
     
     
       7. The method according to  claim 1 , wherein the thin film of carbon nanotubes and the substrate have a transparency to 550 nm light of greater than 85%. 
     
     
       8. A method of directly preparing thin films of carbon nanotubes comprising:
 providing a substrate having top and bottom surfaces; 
 contacting the substrate with an acetone solution and applying ultrasonic energy; 
 contacting the substrate with an isopropanol solution and applying ultrasonic energy; 
 flowing an inert gas over the substrate; 
 immersing the substrate into a carbon nanotube producing catalyst-containing solution; 
 washing the substrate in a non-polar solvent; 
 positioning the substrate in a chemical vapor deposition apparatus; 
 heating the substrate to a temperature of from 800° C. to 900° C. sufficient to produce carbon nanotubes, and 
 contacting a carbon-containing gas with the heated substrate to produce a thin film of carbon nanotubes on both top and bottom surfaces. 
 
     
     
       9. The method according to  claim 8 , wherein the substrate comprises quartz. 
     
     
       10. The method according to  claim 8 , wherein the carbon nanotube producing catalyst comprises at least one metal selected from the group consisting of iron, cobalt, nickel, molybdenum, ruthenium, rhodium, palladium, silver and platinum. 
     
     
       11. The method according to  claim 8 , wherein the carbon nanotubes are comprised of a majority of metallic carbon nanotubes. 
     
     
       12. The method according to  claim 8 , wherein the carbon-containing gas contains at least one member selected from the group consisting of methane, ethane and propane. 
     
     
       13. The method according to  claim 8 , wherein the thin film of carbon nanotubes has a resistance of less than 7500 ohm/square. 
     
     
       14. The method according to  claim 8 , wherein the thin film of carbon nanotubes and the substrate have a transparency to 550 nm light of greater than 85%. 
     
     
       15. The method according to  claim 1 , wherein washing the substrate in the non-polar solvent comprises exposing the substrate to the non-polar solvent for less than ten seconds.